Nano crystals or Quantum dot emissions may be uniquely tuned in wavelength outputs and possess very high conversion efficiencies. These properties may be potentially useful for display applications. Traditional implementation of nano crystals may use a blue Light Emitting Diode (LED) as a pump source. The blue LED pump source allows a portion of the blue wavelength to be converted to green and red wavelengths but also to be used as the emission source for the blue light projected from the Liquid Crystal Display (LCD). One drawback of the technology is that some of the blue LED pump emission spectrum will pass through the conversion layer in an unconverted state and the luminance ratio of the display being biased towards the pumping spectrum.
Polarization recycling filters offer some level of light recycling to increase efficiency. The concept being to recycle a portion of the energy that was not converted in a single pass through the nano crystal.
Another attempt at increasing the conversion of the pump wavelength has been incorporation of the nano crystals in a diffusing medium thus increasing the effective path length of the light. This diffusing medium does increase overall conversion but also suffers from losses into the backlight cavity.
Consequently, a need exists for an effective system and method for increasing spectrum conversion of an blue LED pump.